Power hammer



c. B. coATEs POWER HAMMER Nov. 22, 1932.

Filed Feb. 16, 1928 @M www A TTORNE Y.

Patented Nov. 22j,

Unirse stares Param OFFICE CHARLES B. COATES, OF CLEVELAND, OHI,ASSIGNOR TO CHICAGO PNEUMATIC TOOL COMPANY, OF NEN YORK, N. Y., ACORPORATION F NEW JERSEY POWER HAMMER Application led February 16, 1928.Serial No. 254,845.

i Thisinvention rela-tes to powerr hammers generally but has beendeveloped with particular attention to portable or hand operatedhammers,such as are actuated by an electric motor attached to the hammeror by a ilexible shaft driven by a more remote source of power. i

One object of the invention is to increase the efficiency of powerhammers generally.

Another object is to simplifythe construction and to reduce thelubrication problem. Another object is to cut down the weight and sizeof the portable power hammer. @ther objects will. beapparent from thedetail-ed description which follows. l

In order to illustrate the invention one concrete embodiment thereof isshown in the accompanying drawing in which:

Fig. 1 is a side lelevational view largely in vertical section to showthe details of the hammer; f Y

F ig. 2 is a fragmentary vertical sectional view 0fl the hammer andassociated parts showing th-e relative positions at the end of the powerstroke.

' In the embodiment of the invention chosen for the purpose ofillustration the hammer consists ofa barrel 3 bored out axially toprovidea piston chamber within which reciprocates a free hammerV piston4, the movement of which is controlled andactuated by a cylinder 5 ofsubstantial length whichV telescopes over barrel 3 with aclose slidingiit and has limited reciprocal movement relative to the barrel.

is closed and cooperates with the top of barrel 3 to provide a chamber 6of relatively large diameter as compared with piston chamber 3a.

to By preference barrel 3 extends within a shell 7 to which it isiiXedly secured in any suitable manner, as by a threaded connection at8. The lower end of shell 7 may be split and provided with a clampingbolt 9 to lock barrel 3 securely in place. The proximate end of thebarrel may have a bushing 10 pressed therewithin to receive the shankend of a working tool, such as a drill bit or chisel A, and to disposethe shank in position to receive the blows of hammer piston 4. The

The upper end of cylinder 5A 'the bulk and weight of the tool to aminimum.

To this end a crank shaft 12 is disposed trans'- versely within shell 7-closely adjacent the upper end of barrel 3, the shaft being journaled inbearings 13 and 14 at oppositesides of shell 7. The connection betweenthe crank shaft 12 and cylinder v5 preferably takes the form of a Scotchyoke7 spaced loops or yoke portions 5a having aligned openings beingformed upon the closed head portion of cylinder 5.

i TWhile shaft 12 may be arranged to be driven directly from anysuitable source of power, it is preferable in a tool of the portabletype'havingits own pow-er means to provide for gear reduction betweenthe power shaft and the crank shaft. To this end crank shaft 12 isprovided with a large gear 15 ar,- ranged to mesh with pinion teeth upona power shaft 1G projecting within shell 7. Strength issecured byforming gear 15 integral with shaft 12 and compactness is at'- tained bymakingthe gear cup-shaped and at least partlyl enclosing bearing 14 for`the proximate. end of the shaft. A counter balance 17 may be providedon a ring having a press fit upon shaft 12 adjacent gear 15.

llVhile power shaft 16 may be driven by a flexible shaft or othersuitable means, it is preferable in small portable hammers to make thesame an extension of the rotor shaft for an electric motor 18 supportedin a Casing 19 secured to shell 7. By preference a transfer 90 plate 20is interposed between motor casing 19 and shell 7 and this transferplate may close an opening in shell 7 in line with shaft 12 and throughwhich the latter may be withdrawn. In this construction the ltransferplate supports bearing 14. v The tool is com# pl-eted by a handle 21,which in the present instance is secured both tomoto'r casing 19 andshell 7. The power cable 22 to motor 18 may be connected to handle 21which may 100 stroke, ports b are closed and the air in chamber G iscompressed causing hammer piston 4 to be forced downwardly by the airpressure on its upper end. rl`he area of the compression chamber 6 is somuch larger than the area of the piston that the latter moves muchfarther' and faster on its downward stroke thandoes cylinder 5and itapproaches the shank of the workingv tool with con,- siderable pressureback of it. d ust before the blow is struck (Fig. 2) piston 4 uncoversone or more radial ports 3b with which a corresponding number of ports5c in cylinder 5 register when the cylinder is at the lower limit of itsstroke. rlhis relieves the pressure in chamber 6 and the upper portionof piston chamber '3a by permitting the same to discharge into the spacewithin shell Y. As cylinder 3 begins its rearward stroke ports 5c passout of register with ports 3b and the suction produced in chamber 6 incooperation with the atmospheric pressure, which has access to the lowerend of piston l through ports ll, causes the return movement of piston lwhich continues until the suction pressure in chamber 6 is broken by theuncovering of ports 5b whereupon piston -t is ready for its powerstroke, thus completing the cycle.

The described arrangement of axially spaced ports 5?) and 5c in cylinder5 in conjunction with the enclosed space atatmospheric pressure withinshell 7 notonly insures positive movement of piston l in both directionsbut keeps all dust and dirt out of the reciprocating parts of thehammer. The differential areas of hammer piston 4l and cylinder 5 aswell as the proper positioning of ports 5b, 5c and SZ) are veryimportant in securing efficient operation of the hammer. ln a practicalembodiment of the invention as disclosed the stroke of cylinder 5 is {B-of an inch while the stroke of piston 4: is from 1/2 to fig. The blowsare rapid and are much-more powerful than it has been possible to securewith piston driven hammers of this general type.

` The compactness and short stroke of the moving parts assist materiallyin reducing both wear and lubrication troubles. ln order to maintain atight seal between cylinder 5 and fixed barrel 3, as well as to insureproper 4 lubrication of the same, the barrel is providedv at a pointalways covered by cylinder 5 with a deep groove 23 of substantial width,which is filled with suitable packing material 2li, such as cotton,which is saturated with lubricant;

While the invention has been herein disclosed in what is now consideredto be its preferred form, it is to be understood that the invention isnot limited to the specific details thereof, but covers all changes,modifications and adaptations within the scope of theappended claims.

l claim as my invention:

1. A power hammer comprising a barrel, a piston slidable therein, acylinder enclosing said barrel and having a bearing upon the exterior ofthe latter, and means for reciprocating said cylinder upon said barrel.

2. A power hammer comprising a fixed barrel, a piston slidable therein,a cylinder i,

cooperating with said barrel to provide an expanding and contractingchamber above said barrel.

3. A power hammer 'comprising a fixed barrel, a piston slidable therein,a cylinder cooperating with said barrel to provide an expanding andcontracting chamber above said barrel, and means for admitting air tosaid chamber in one position of said parts.

t. A power hammer comprising a fixed barrel, a piston slidable therein,a cylinder cooperating with said barrel to provide an expanding andcontracting chamber above said barrel, and means for releasing air fromsaid chamber in one position of said parts.

l5. A ower hammer comprising a fixed barrel, a piston slidable therein,a cylinder cooperating with said barrel to provide an expanding andcontracting chamber above said barrel, and means controlled jointly `bysaid piston and by said cylinder for releasing air from said chamber inone position of-said parts.

6. A power hammer comprising a fixed barrel, a piston slidable therein,a cylinder cooperating with said barrel to provide an expanding andcontracting chamber above said barrel, and cooperating means on saidcylinder and said barrel forestablishing com- Yitc ila

mimication with said chamber and surround- Y ings in certain positionsof said parts.

7. A power hammer comprising a barrel, a piston slidable therein, acylinder of substantial length having a closed end and sleeved over saidbarrel with a close sliding tit, means for reciprocating said cylinderupon said barrel, and means including ports in said cylinder forestablishing communication with the'chamber formed by the closed end ofthe cylinder in certain positions of the latter.

8. A power hammer comprising a barrel, a piston slidable therein, acylinder of substantial length having a closed end and sle-eved oversaid barrel with a close sliding lit, means for reciprocating saidYcylinder iis upon said barrel, said barrel having an annular groove inits exterior in a position to be covered at all times by said cylinder,and lubricant in said groove.

9. A power hammer comprising a shell, a barrel secured within saidshell, a hammer piston reciprocable within said barrel, a cylinder ofsubstantial length having a closed end and sleeved over said barrel witha close sliding fit, means for reciprocating said cylinder over saidbarrel for expanding and contracting the chamber formed therebetween bythe closed end of the cylinder, and means controlled by said cylinderfor establishing conimunication between said chamber and the interior ofsaid shell. i

10. A power hammer comprising a` shell, a barrel secured within saidshell, a hammer piston reciprocable within saidbarrel, a cylinder ofsubstantial length having a closed end and sleeved over said barrel witha close sliding fit, means for reciprocating said cylinder over saidbarrel for expanding and contracting the chamber formed therebetween bythe closed end of the cylinder, and means including axially spaced portsin said cylinder for establishing communication between said chamber andthe interior of said shell in a plurality of positions of said cylinder.

11. A power hammer comprising a shell, a barrel secured within saidshell, a hammer piston recipiocable within said barrel, a cylinder ofsubstantial length having a closed end and sleeved over said barrel witha close sliding fit, means for reciprocating said cyl-Y inder over saidbarrel for expanding and contracting the chamber formed therebetween bythe closed end of the cylinder, said barrel having one or more radialports therein under control of said piston, and said cylinder having oneor more ports arranged to register with said barrel ports in oneposition of said cylinder.

12. A power hammer comprising a shell, a barrel secured within saidshell, a cylinder sleeved over said barrel with a close sliding fit, acrank shaft journaled in said casing transversely above said barrel andclosely adjacent thereto, a driving connection between said shaft andsaid cylinder, and means for rotating said shaft.

13. A power hammer comprising a shell, a barrel secured within saidshell, a cylinder sleeved over said barrel with a close sliding fit, acrank shaft journaled in said shell transversely above said barrel andcloselyY adjacent thereto, a Scotch yoke connection between said shaftand said cylinder, and a power shaft entering said shell and arranged torotate said crank shaft. j

14E. A power hammer comprising a shell, a barrel secured within saidshell, a free hammer piston reciprocable in said barrel, a reciprocablemember cooperating with said barrel for actuating said piston, a shaftextend- 'ing ltransversely above said barrel and closely adjacentthereto, a driving connection between-"said shaft andsaid member,'bearings for said shaft onopposite sides of said shell, a powershaftprojecting within said shell, and driving connection between said firstnamed shaft and' said power shaft including acup shaped gear on saidfirst named shaft at least partly enclosing one of said bearings. 1,15.`In apower hammer, in combination, a shell having an end opening and aside opening, a barrel insertable within said shell shaft and drivingconnection for said cylinder insertable through said side opening.

16. In a power hammer, in combination, a shell having an end opening anda side opening, a barrel insertable within said shell through said openend `and adapted and arranged to close said open end and to be fixedlysecured therein, a reciprocable cylinder on said barrel withdrawablewith the latter through said end opening, a crank shaft and drivingconnection for said cylinder insertable through said side opening, atransfer plate secured to said shell for closing said opening andproviding a bearing for said shaft, and a motor secured to said plateand arranged to drive said shaft.

17. A power hammer comprising a fixed barrel, a hammer piston slidabletherein, a cylinder in telescoping relation with said barrel to providean expanding and contracting chamber above the latter to edect movementof said piston, and means disposed in the telescoping-zone of saidbarrel and of said cylinder for lubricating the same.

18. A power hammer comprising cylindrical members in telescopingrelation, the inner of 'said members being fixed and the outer membermovable to provide an expanding and contracting chamber above said fixedmember, and a hammer piston slidable within said inner member and movedas a result of the variations in said chamber, one of said membershaving a recess for lubricant in its telescoped portion.

19. A power hammer comprising cylindrical members in telescopingrelation, the inner of said members being fixed and the outer membermovable to provide an expanding and contracting chamber above said fixedmember, a hammer piston slidable within said inner member and moved as aresult of the variations in said chamber, one of said members havinganannular recess in its telescoped portion, and packing materialsaturated with lubricant filling said recess.

20. A power hammer having concentric members engaging one another with asliding lit and arranged for relative movement in an' axial direction,certain portions of said members being retained in telescoping relationin all positions of relative movement, the inner member being fixed andthe outer member movable thereon to provide an expanding and contractingchamber above said fixed member, a hammer piston slidable Within saidinner member and moved as a result of variations in said chamber, saidinner member having an annular recess in its exterior Within itscontinuously telescoped portion, and packing material saturated Withlubricant filling said recess. vSigned by me at Cleveland, in the countyof Cuyahoga and State of Ohio this 8th day of February, 1928.

A CHARLES B. COATESU

